This invention generally relates to escalator drive mechanisms. More particularly, this invention relates to a failure detection and backup arrangement for use in an escalator drive mechanism.
Escalators are passenger conveyors that typically carry passengers between landings at different levels in buildings, for example. A chain of steps typically is driven using a motorized assembly. There are a variety of motorized assemblies proposed or currently in use. There are several possible ways in which the drive torque from the motor to the step chain can be interrupted.
When there is a failure of drive transmission between the motor and the step chain, there is a need to control the position of the escalator steps. Without the motive force of the motor, normal gravitational forces may cause undesirable movement of the escalator steps, for example. There is a need for an arrangement that controls movement of the escalator step chain and steps even under conditions when the normal drive mechanism cannot operate as normally intended.
This invention provides a mechanism for controlling the movement of the escalator even under conditions where the normal drive arrangement cannot operate as intended. Additionally, this invention provides an indication of when the normal drive operation has failed.